Field of the Invention
This invention relates, generally, to blowout preventers for subsea applications, and more specifically, to an autonomous blowout preventer to monitor the material inside the blowout preventer and measure the critical parameters for performance of the blowout preventer.
Description of the Prior Art
Formation hydrocarbons (kick) may flow into a well during drilling, thereby “kicking” or displacing the drilling fluids. The rig crew must watch for a kick and shut-in the well before it evolves into a blowout as illustrated in FIG. 2. Early appropriate intervention is the best solution as a kick may evolve rapidly resulting in a short window of opportunity to arrest the blowout and bring the well under control.
The Blowout Preventer, also referred to herein as “BOP”, comprises a number of valves and it is placed on top of a well to facilitate daily operations and act as the last line of defense against the uncontrolled flow of hydrocarbons. However, the history of BOP performance during a well blowout and scrutiny of BOP designs reveal that BOP's are designed more as Operation-Aids for a well that is under control; not as Blowout-Arrestors to prevent the uncontrolled flow of hydrocarbons as illustrated in FIG. 6A-FIG. 6F. Well operations are static or quasi-static under the control of the rig crew while a well blowout is a forceful dynamic event, often beyond the control of the rig crew and beyond the capabilities of today's BOP designs. This has resulted in a number of disasters, like IXTOC 1 and MACONDO, resulting in environmental disasters and loss of life. As opposed to daily well operations, the appropriate blowout action cannot be established without real-time feedback of critical parameters followed by a calculated rapid response.
Therefore, there is a need to define the BOP distinct functions; to correct the BOP design deficiencies; to monitor critical parameters to identify a kick early-on; to track the kick evolution and to optimize the BOP operation and sequencing to arrest the event under the various realistic conditions to bring the well under control. The last line of defense should be a Blowout-Arrestor, not an Operations-Aid. It should be understood that a seaworthy Blowout-Arrestor may function as a seaworthy Operations-Aid, but not the other way around as experience has proven.